Favorable response of pediatric stem cell recipients to human protein C concentrate substitution for veno-occlusive disease

A stitch in time saves nine: timely use of N-acetyl cysteine (NAC) for chemotherapy-induced veno-occlusive disease (VOD)-is it a cost-effective alternative?

Chemotherapy-induced veno-occlusive disease (VOD) is a rare liver dysfunction seen among pediatric cancer patients which could lead to severe morbidity and mortality. Defibrotide is the commonly used antidote in the management of both stem cell transplant and chemotherapy-associated VOD along with liver supportive measures. Defibrotide is costly and generally not accessible to majority of patients treated at resource poor settings. In this report, we describe the successful management of chemotherapy-induced VOD with timely administration of N-acetyl cysteine.

Early vascular endothelial complications after hematopoietic cell transplantation: Role of the endotheliopathy in biomarkers and target therapies development

This work aims to review the role of endothelial dysfunction underlying the main complications appearing early after autologous and allogeneic hematopoietic cell transplantation (HCT). The endothelial damage as the pathophysiological substrate of sinusoidal obstruction syndrome (SOS) is well established. However, there is growing evidence of the involvement of endothelial dysfunction in other complications, such as acute graft-versus-host disease (aGVHD) and transplant-associated thrombotic microangiopathy (TA-TMAs). Moreover, HCT-related endotheliopathy is not only limited to the HCT setting, as there is increasing evidence of its implication in complications derived from other cellular therapies. We also review the incidence and the risk factors of the main HCT complications and the biological evidence of the endothelial involvement and other linked pathways in their development. In addition, we cover the state of the art regarding the potential use of the biomarkers of endotheliopathy in the prediction, the early diagnosis, and the follow-up of the HCT complications and summarize current knowledge points to the endothelium and the other linked pathways described as potential targets for the prevention and treatment of HCT-complications. Lastly, the endothelium-focused therapeutic strategies that are emerging and might have a potential impact on the survival and quality of life of post-HCT-patients are additionally reviewed.

How I manage sinusoidal obstruction syndrome after haematopoietic cell transplantation

Sinusoidal obstruction syndrome (SOS), also called veno-occlusive disease of the liver, is one of the most relevant complications of endothelial origin that appears early after haematopoietic cell transplantation (HCT). Despite its relatively low incidence and the fact that most cases of SOS resolve spontaneously, the cases that evolve to multi-organ failure (MOF; severe SOS) have a mortality rate higher than 80% and represent one of the major clinical problems after HCT. For this reason, transplantation teams must have a pre-established policy regarding preventive measures in high-risk patients, strict daily control of weight and fluid balance during HCT, homogeneous diagnostic criteria, appropriate complementary studies for a correct differential diagnosis and measures to prevent and manage hepatorenal syndrome; in addition they must also be ready to start early treatment with defibrotide in patients with a possible severe SOS. Due to the lack of definitive evidence to enable the establishment of general recommendations in the management of SOS, this review analyses all of these aspects based on the author's personal experience.

Non-activated protein C rescue treatment in Wilms tumour associated hepatic sinusoidal obstructive syndrome

Hepatic sinusoidal obstructive syndrome (HSOS) is a frequent complication in patients undergoing haematopoietic stem cell transplant (HSCT), and more rarely, in paediatric patients receiving conventional chemotherapy for solid tumours. Its diagnosis relies on a combination of clinical signs and symptoms such as hepatomegaly, jaundice, weight gain and fluid retention. HSOS treatment is primarily based on supportive care and anti-fibrinolytic agents. Here we report two patients affected by Wilms tumour who developed life-threatening HSOS that failed to respond to conventional treatment. Both patients recovered after receiving aggressive supportive treatment that included administration of non-activated protein C (Ceprotin®--Baxter).

Hepatic veno-occlusive disease after hematopoietic stem cell transplantation: Prophylaxis and treatment controversies

Hepatic veno-occlusive disease (VOD), also known as sinusoidal obstruction syndrome, is a major complication of hematopoietic stem cell transplantation and it carries a high mortality. Prophylaxis for hepatic VOD is commonly given to transplant recipients from the start of conditioning through the early weeks of transplant. However, high quality evidence from randomized controlled trials is scarce with small sample sizes and the trials yielded conflicting results. Although various treatment options for hepatic VOD are available, most have not undergone stringent evaluation with randomized controlled trial and therefore it remains uncertain which treatment offers real benefit. It remains controversial whether VOD prophylaxis should be given, which prophylactic therapy should be given, who should receive prophylaxis, and what treatment should be offered once VOD is established.

Hepatic veno-occlusive disease: a chemotherapy-related toxicity in children with malignancies

Hepatic veno-occlusive disease (VOD) is a major manifestation of liver toxicity associated with conventional and high-dose chemotherapy in children affected by hematologic malignancies and certain solid tumors. Clinically, patients present with jaundice, painful hepatomegaly, and fluid retention, which may evolve into multi-organ failure, a hallmark of severe disease. The pathogenesis is complex and not completely understood, but the damage to sinusoidal endothelium, typically caused by toxic metabolites released from antineoplastic drugs, is thought to play a crucial role, together with cytokine activation, immune deregulation, and coagulopathy. Diagnosis is based on clinical criteria supported by characteristic ultrasound findings, with the gold standard investigation being hepatic-venous pressure gradient measurement and biopsy. Several treatment options have been tested; the most convincing approach to date is the use of defibrotide, a novel oligonucleotide with antithrombotic and antiplatelet aggregating properties, as well as endothelial-stabilizing effects. This agent, together with other specific forms of supportive care, has shown efficacy in the treatment of established VOD and promising results in the prevention of VOD in pediatric patients receiving chemotherapy.

The fibrinolytic mechanism of defibrotide: effect of defibrotide on plasmin activity

Fibrinolytic activity has been shown to be reduced in many vascular diseases, including hepatic veno-occlusive disease after stem cell transplantation, a microangiopathy characterized by sinusoidal endothelial cell injury. Defibrotide is a polydisperse oligonucleotide with antithrombotic, profibrinolytic, anti-ischemic, and antiadhesive properties. Numerous clinical studies have shown promising activity of defibrotide in the treatment and prevention of veno-occlusive disease, with minimal toxicity. In corollary laboratory studies, defibrotide has been shown to decrease plasminogen activator inhibitor-1, increase tissue plasminogen activator levels, and increase overall plasma fibrinolytic activity in patients. Plasmin, a potent and nonspecific serine protease, plays a pivotal role in fibrinolysis by virtue of its ability to effectively degrade fibrin clots. In this study, defibrotide increases the activity of plasmin in hydrolyzing its substrate in a dose-dependent and length-dependent manner. Similar concentration-dependent effects of defibrotide were observed when plasmin was generated by tissue plasminogen activator or urokinase activation of plasminogen. In contrast, defibrotide had no direct effect on the activation of plasminogen to plasmin. Defibrotide was also able to enhance the activity of plasmin in degrading fibrin clot formed from fibrinogen, plasminogen, and thrombin. This effect was also concentration-dependent and directly correlated with the enzymatic activity of plasmin. This study therefore demonstrates that defibrotide is capable of enhancing the activity of plasmin and so contributes to its fibrinolytic activity. Taken together, these results support the effect of defibrotide in restoring the fibrinolytic vascular phenotype, in microangiopathic conditions such as veno-occlusive disease.

Plasma protein C is a useful clinical marker for hepatic veno-occlusive disease (VOD) in stem cell transplantation

BACKGROUND

Hepatic veno-occlusive disease (VOD) is one of the most serious complications in stem cell transplantation (SCT). Although plasma protein C activity decreases in VOD after SCT, the timeframe of plasma protein C activity decreases during SCT is not known.

PROCEDURE

We examined levels of plasma protein C serially during the course of SCT to determine the critical level and risk factors for VOD.

RESULTS

Of 151 children who received SCT, 12 of them (7.9%) developed VOD. The mean minimum protein C activity in patients with VOD was significantly lower compared to that in patients without VOD (P < 0.0001). Receiver operating characteristic curve analysis revealed that the critical plasma protein C activity (cut-off point) for VOD was identified to be 34.5% with high sensitivity (100%) and specificity (83.3%), and the reduction of plasma protein C below the cut-off level (day +6.50 +/- 2.43) was observed mostly prior to the onset of VOD (day +7.33 +/- 2.64). The patients receiving melphalan in conditioning were found to be at high risk for VOD (P = 0.003). Among the melphalan containing regimens, melphalan + carboplatin + etoposide was a significant risk factor for depression of plasma protein C (P = 0.037).

CONCLUSION

Plasma protein C level was a useful parameter of VOD after SCT, and activity below 34.5% was critical for VOD. The use of melphalan in conditioning causes a high risk for VOD.

Defibrotide for the treatment of severe hepatic veno-occlusive disease and multiorgan failure after stem cell transplantation: a multicenter, randomized, dose-finding trial

Therapeutic options for severe hepatic veno-occlusive disease (VOD) are limited and outcomes are dismal, but early phase I/II studies have suggested promising activity and acceptable toxicity using the novel polydisperse oligonucleotide defibrotide. This randomized phase II dose-finding trial determined the efficacy of defibrotide in patients with severe VOD following hematopoietic stem cell transplantation (HSCT) and identified an appropriate dose for future trials. Adult and pediatric patients received either lower-dose (arm A: 25 mg/kg/day; n = 75) or higher-dose (arm B: 40 mg/kg/day; n = 74) i.v. defibrotide administered in divided doses every 6 hours for > or =14 days or until complete response, VOD progression, or any unacceptable toxicity occurred. Overall complete response and day +100 post-HSCT survival rates were 46% and 42%, respectively, with no significant difference between treatment arms. The incidence of treatment-related adverse events was low (8% overall; 7% in arm A, 10% in arm B); there was no significant difference in the overall rate of adverse events between treatment arms. Early stabilization or decreased bilirubin was associated with better response and day +100 survival, and decreased plasminogen activator inhibitor type 1 (PAI-1) during treatment was associated with better outcome; changes were similar in both treatment arms. Defibrotide 25 or 40 mg/kg/day also appears effective in treating severe VOD following HSCT. In the absence of any differences in activity, toxicity or changes in PAI-1 level, defibrotide 25 mg/kg/day was selected for ongoing phase III trials in VOD.